diff --git a/packages/orm/src/client/crud/dialects/postgresql.ts b/packages/orm/src/client/crud/dialects/postgresql.ts
index 41d9b9006..25345ada0 100644
--- a/packages/orm/src/client/crud/dialects/postgresql.ts
+++ b/packages/orm/src/client/crud/dialects/postgresql.ts
@@ -409,7 +409,7 @@ export class PostgresCrudDialect<Schema extends SchemaDef> extends LateralJoinDi
     }
 
     override buildArrayLength(array: Expression<unknown>): AliasableExpression<number> {
-        return this.eb.fn('array_length', [array]);
+        return this.eb.fn('array_length', [array, sql.lit(1)]);
     }
 
     override buildArrayValue(values: Expression<unknown>[], elemType: string): AliasableExpression<unknown> {
diff --git a/tests/e2e/orm/policy/isempty-function-pg.test.ts b/tests/e2e/orm/policy/isempty-function-pg.test.ts
new file mode 100644
index 000000000..9af038d02
--- /dev/null
+++ b/tests/e2e/orm/policy/isempty-function-pg.test.ts
@@ -0,0 +1,36 @@
+import { createPolicyTestClient } from '@zenstackhq/testtools';
+import { describe, expect, it } from 'vitest';
+
+describe('isEmpty function in policies using Postgres', () => {
+    it('does not throw an error', async () => {
+        const schema = `
+model User {
+    id        Int      @id @default(autoincrement())
+    roles     Role[]
+
+    @@allow('all', true)
+    @@deny('create', isEmpty(roles))
+}
+
+enum Role {
+    AUTHOR
+    EDITOR
+}
+    `;
+
+        const client = await createPolicyTestClient(schema, {
+            usePrismaPush: true,
+            provider: 'postgresql',
+        });
+
+        await expect(client.user.create({
+            data: {
+                id: 1,
+                roles: ['AUTHOR'],
+            },
+        })).resolves.toMatchObject({
+            id: 1,
+            roles: ['AUTHOR'],
+        });
+    });
+});